This doesn't follow. It's incredibly efficient, in time and effort terms, to get around sprawl. You just drive at 65mph on the wide-open freeways and up the parking lot with plenty of open space in front of every conceivable destination. I've never spent more than 30 minutes making a point-to-point hop where both points are in sprawl. Average case, more like 10. Traffic jams == not sprawl-y enough.
Thirty minutes for any public transit trip in San Francisco or Chicago (at least the parts I can afford) is like a once-a-year pop-the-champagne-corks celebration. Ten, forget it. Not gonna happen ever unless it's the corner store. Getting anywhere useful is usually abut 50 minutes. (I'm pretty sure this is the CTA's SLA. No matter the distance - past a point, roughly 50 minutes. Implies some design effort and a sophisticated balancing of slower and faster lines).
Sure, bus tickets are cheaper than car ownership, but our time is worth something too.
>just agglomerations of many towns without a center
This is precisely what the pro-density anti-car people on HN advocate: dense walkable neighborhoods, with no real solution for medium distance transportation. Tiny markets where local businesses get to price-gouge you because going to a competitor means lighting your afternoon on fire.